Flexible piezoelectric pressure sensor based on polydopamine-modified BaTiO3/PVDF composite film for human motion monitoring

Abstract

Flexible pressure sensors based on piezoelectric materials have been intensively investigated for their wide applications in wearable electronics. However, traditional films based on inorganic/organic composite piezoelectric materials face the bottleneck of defects and cracks or poor dispersion, which hinders the performance of pressure sensors. Herein, polydopamine (PDA) was introduced as a surface modification agent to modify barium titanate (BaTiO3, BTO), which was then blended with poly(vinylidene fluoride) (PVDF) matrix in different ratios to form uniform and homogeneous PDA@BTO/PVDF composites. Afterwards, the flexible piezoelectric pressure sensor was fabricated by a facial solution-casting method. This PDA-modification strategy can improve the dispersion of BTO into PVDF matrix, as well as reduce the interface hole defects and cracks between the two components. As a result, the 17 wt% PDA@BTO/PVDF sensor exhibited a fast response of 61 ms and a remarkable piezoelectric output voltage of 9.3 V, which showed obvious improvement as compared to the pristine PVDF and BTO/PVDF composite counterparts. In addition, as an energy supplier, the sensor could produce a maximum power of 0.122 μW/cm2 even with high load resistance of 70 MΩ. This pressure sensor was sensitive to various human motions, showing great potential in the applications of wearable electronics.